Re: Johnson piston ring chart question

[r-c]

It would appear you would need a scale that could compress the ring. Where to find one? Don’t know. It would also appear you need a jig of some sort to keep the ring from twisting while under compression. None of this is addressed in the service manuals and doesn’t appear after the early 1050’s books.
This is something we never have done, at least in my experience. We put the ring in the cylinder to check butt gap and as long as the ring doesn’t fall out of the cylinder it is good.
The static spring tension against the cylinder wall has little to do with operation. A too strong ring pressure against the cylinder wall will help static pressure tests with your compression gage. So what? And if you had one of our racing motors with mulit-ports and the spring tension is too much, it catches a port and breaks!
A good seal always helps starting. However too much pressure will wear out the ring and cylinder earlier in life.
The whole ideal is to have clearance between the ring and land, about 0.003" and space behind the ring (which the manufacturers have figured out) for the gas pressure to do the sealing on the compression stroke.
Some worry about things that don’t matter. I have stated that life at 5,000 rpm is much different than 10,000 rpm!